In short, the electric light was not yet
'subdivided.'
Edison, in common with others, turned his attention to the subject, and
took up the neglected incandescent lamp. He improved it by reducing the
rod of carbon to a mere filament of charcoal, having a comparatively
high resistance and resembling a wire in its elasticity, without being
so liable to fuse under the intense heat of the current. This he
moulded into a loop, and mounted inside a pear-shaped bulb of glass.
The bulb was then exhausted of its air to prevent the oxidation of the
carbon, and the whole hermetically sealed. When a sufficient current
was passed through the filament, it glowed with a dazzling lustre. It
was not too bright or powerful for a room; it produced little heat, and
absolutely no fumes. Moreover, it could be connected not in but across
the main circuit of the current, and hence, if one should break, the
others would continue glowing. Edison, in short, had 'subdivided' the
electric light.
In October, 1878, he telegraphed the news to London and Paris, where,
owing to his great reputation, it caused an immediate panic in the gas
market. As time passed, and the new illuminant was backward in
appearing, the shares recovered their old value.
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